Search

Ruthenium nitrosyl complexes are fascinating versatile photoactive molecules that can either undergo NO linkage photoisomerization or NO photorelease. The photochromic response of three ruthenium mononitrosyl complexes, trans-[RuCl(NO)(py)4]2+, trans-[RuBr(NO)(py)4]2+, and trans-(Cl,Cl)[RuCl2(NO)(tpy)]+, has been investigated using density functional theory and time-dependent density functional theory. The N to O photoisomerization pathways and absorption properties of the various stable and metastable species have been computed, providing a simple rationalization of the photoconversion trend in this series of complexes. The dramatic decrease of the N to O photoisomerization efficiency going from the first to the last complex is mainly attributed to an increase of the photoproduct absorption at the irradiation wavelength, rather than a change in the photoisomerization pathways.